There has been known such a technology that a position detecting device, such as a digitizer, is applied to a game apparatus, the position detecting device having a combination of a coordinates pointing device and a pointed-coordinates detecting device. For example, as disclosed in Patent Document 1, there has been known a game apparatus for playing shogi (Japanese chess) that includes a chessboard as a digitizer and a chess piece as a pointer to be placed on the digitizer. Specifically, the digitizer has a sensor to detect a position of the pointer in such a way that an induction voltage is induced in a loop coil provided in the sensor side corresponding to a radio wave generated by a coil in a tuning circuit embedded in the pointer. Further, the digitizer detects a direction and the front and back surfaces of the pointer such that the output level of the radio wave output from the pointer-side coil differs in the front and rear sides and the front and back surfaces of the pointer.
On the other hand, with the recent advance in RFID (radio frequency identification) technology, a technique of RFID data carriers applied to in a game field has been known. For example, as disclosed in Patent document 2, when a game piece on hand is placed in a communication area of an RFID reader-writer before starting a game, ID information stored in the game piece is read out, and a data carrier list is produced with the read ID information associated with a player. After starting the game, when the game piece is placed in the communication area of the RFID reader-writer, the ID information is read, and it is determined to which player the placed game piece belongs with reference to the data carrier list. For example, when a game piece, having a figure formed in a game item, is placed in the communication area of the RFID reader-writer, it is checked to which player the read ID information corresponds in the data carrier list, and the effect due to the use of the game item is attributed to the corresponding player.
Patent document 1: JP-Tokukai-Hei-07-323109A
Patent document 2: JP-Tokukai-200-325970A